1. Field of the Invention
The present invention relates to an image encoding device and image encoding method, an image decoding device and image decoding method, a recording medium and a motion parameter detecting device and motion parameter detecting method and more particularly relates to an image encoding device and image encoding method, an image decoding device and image decoding method, a recording medium and a motion parameter detecting device and motion parameter detecting method capable of reducing the amount of code generated by multiplexing encoded image data relating to characteristic points of a moving image and motion vectors for chains linking these characteristic points. The present invention also further relates to a motion parameter detecting device and a motion parameter detecting method capable of accurately detecting motion parameters expressing the motion of image linking points for chains etc. linking characteristic points of an image, capable of being applied to the above-mentioned image encoding.
2. Description of Related Art
Conventionally, highly efficient coding methods have been adopted for efficiently compressing image data using few code words in devices such as devices for transmitting images across limited transmission bands or devices for recording to recording media of limited storage capacity. Methods such as methods where, for example, inputted images undergo an orthogonal transformation using DCTs (Discrete Cosine Transforms) and are then appropriately quantized in accordance with peoples' sense of sight every frequency band or methods where an image is divided into sub-bands by a wavelet base (wavelet transform) and encoding is performed with a weighting given to each band are well known as highly efficient image encoding methods. According to these methods, visual distortion becomes difficult to notice and a high compression efficiency can be achieved.
However, if the compression efficiency is increased in these encoding methods, effects such as block distortions which are not visually pleasing become more striking.
Further methods such as structure extracting encoding methods where points characteristic to the structure of the image (characteristic points such as, for example, points (pixels) comprising edges) are extracted, the image data occurring at the characteristic points is efficiently encoded and the characteristic points of the image are detected, such as in U.S. patent application Ser. No. 08/457,830, U.S. Pat. No. 5,757,972, have been put forward by the applicant as encoding methods where visually damaging distortion does not occur even under a high compression rate.
However, with conventional image encoding devices where encoding was carried out by detecting characteristic points, because still images were taken as the encoding target, when moving images were taken as the encoding target, the encoding efficiency was poor when compared with transform encoding methods including, for example, motion compensation processing and DCT processing etc. because time consuming components were removed.
As the present invention sets out to resolve these kinds of problems, it is the object of the present invention to provide an image encoding device and image encoding method, an image encoding device and image decoding method and recording medium capable of increasing the compression efficiency while an image is being compression encoded using a structure extraction encoding method.
It is a further object of the present invention to provide a motion parameter detecting device and a motion parameter detecting method capable of rapidly detecting accurate motion parameters and capable of being applied to an image encoding device.